Yeah, if there is no tenant context, you will just get "There is no account" .So even though you are correct, this is not the solution i am afraid.The login goes swimmingly, its just that Teams kicks me out, i also get the following error in Azure AD sign in log:"Status: FailureSign-In Error Code: 50085Failure Reason: Refresh token needs social IDP login. Have user try signin-in again with username-password."

(which i have tried, different browsers, inkognito mode, cleared history etc)

I don't think Teams supports currrently "direct" signin with Gmail accounts (This for sure is coming) so you need a MSA to be able to get there...in the case of SPO it can be different due to the improvements in guest access done by the SPO and ODFB Team in the last months

Were you ever able to resolve this using the gmail federation rather than reverting back to using Microsoft accounts for Google users? We're seeing the same behavior and I'd hate to roll back the Google federation feature.

@Juan Carlos González Martín - Several users at my company are experiencing intermittent issues with Gmail accounts, specifically when a meeting request is sent (whether it was created in Teams or Outlook). When meeting request email is sent to users with Gmail accounts, often they are returned with the following error:

This is the mail delivery agent at Symantec Email Security.cloud. I was unable to deliver your message to the following addresses: user@gmail.comReason: 550-5.7.1 [67.219.246.116 14] Messages missing a valid address in From:550 5.7.1 header, or having no From: header, are not accepted. m1si4208096qvb.184 - gsmtp

The screenshot is shown below.

This occurs more times than not yet it is intermittent. I have had no issues with emails going to Yahoo.com emails. Do we need to avoid Gmail user accounts for guest access moving forward?

@mikemq - Since I originally posted, I have noticed gmail accounts have behaved intermittently in regards to if the user receives the "You have been added to a Teams site" email. Lately it seems to have gotten better and I have not heard of one of my users who failed to get the invite email from Teams.